Liquid seal level gauge



Dec. 5, 1950 H. A. QUIST 2,532,940

LIQUID SEAL LEVEL GAUGE Filed Nov. 16, 1946 2 Sheets-Sheet 1 IN V EN TOR.

H mzd A. 011m Mar/40M A'I'TOR NEyzs Patented Dec. 5, 1950 LIQUID SEAL LEVEL GAUGE Harold A. Quist, Elkton, Md., assignor to Sun Oil Company, Philadelphia, Pa., a corporation of New Jersey Application November 16, 1946, Serial No. 710,280

4 Claims.

This invention relates to devices for measuring the level of fluids in tanks or other containers and, more particularly, to that class of measuring devices adapted for use in sealed containers whereby the level of the tank contents is measured by the height of a sealing fluid in a measuring tube.

Fluid level gauges of the float and lever type are often unreliable in their indications, inconvenient to use and complicated in construction. Especially where the contents of the tanks to be gauged is a dense and highly viscous material, or is very volatile, the float type of valve is not a reliable level indicator. A measuring apparatus which can be corrected rapidly and easily for gaseous conditions and which is independent of mechanical error or failure is most desirable. The conditions found in the petroleum industry where large storage tanks are used to hold liquids of varying densities, viscosities and volatilities, require a level gauge to function Within a sealed tank, operate under conditions existing within the tank, and be free of mechanical difficulties.

A primary object of this invention is, therefore, to provide a tank gauge which does not use floats, lever arms, or other mechanical means for indicating the level of the tank contents.

Another object is to provide a level gauge where the level of the tank contents is indicated by a separate sealing fluid in a measuring tube.

Yet another object is to provide an apparatus for transferring the fluid pressure of the tank contents to the measuring and sealing fluid without the use of diaphragms or other complicated mechanisms.

Still another object is to provide a liquid level gauge wherein the measuring element is a fluid which can be changed as required by the nature of the tank contents to be measured. theclimate, temperature and other outside conditions which affect the accuracy of tank gauging.

A further object of this invention is to provide a liquid level indicating means which will operate under the actual pressure conditions existing within the tank, thereby attaining a high degree of accuracy in the measurement of the level of the tank contents.

Still a further object is to provide a liquid level indicator which will operate unde conditions where the tank is sealed, thereby obtaining an accurate measure of the contents, and in the case of volatile liquids, preventing the escape of the gases and the consequent danger to the attending workmen.

The above and other objects, together with the novel features of this invention, will be apparent from the following description and the accompanying drawings, of which:

Figure 1 is a View ShOWiIlg a level gauge as assembled for operation where the measuring fluid has a specific gravity lower than the specific gravity of the tank contents.

Figure 2 is a sectional view along lines 2--2 of Figure 1.

Figure 3 is a view showing a level gauge as assembled for operation where the measuring fluid is of a specific gravity higher than the specific gravity of the tank contents.

Figure 4 is a sectional view along lines 4-4 of Figure 3.

Figure 5 is a view of a measurin means.

In Figure 1 the liquid level gauge of my invention designed to be used with a measuring fluid or sealing medium IQ of specific gravity lower than the specific gravity of the tank contents 20, comprises a measuring tube II which in the preferred embodiment is entirel enclosed within the tank I2 except for a projection through the top of the tank to admit a measuring rod such as is shown in Figure 5 through plugged opening i3, and at the bottom of the tank when it projects through the tank to a valve connection I4, thence returning inside the tank to connect with the top of the sealed chamber I5, the front face of which is exterior to the tank I2. A gas pressure equalizing pipe or line I6 connects the measuring tube I I Where it projects through the top of the tank I2 to the gas space within the tank as shown. This line I 6 is valved by a. pressure equalizing cock II thereby adjusting the gas pressure in the measuring tube II to the conditions existing within the tank I2. A second tube I-S connects the bottom of the sealed chamber I5 to valve I9 by piercing the side of the tank I2 and then returns inside the tank where it is open to pressure of the tank contents generally denoted by 20. The two ends of the second tube I8 are turned downward into wells 2| and 22 respectively which prevent clogging of the tube Is by the sediment from the tank contents.

A sectional view more clearly showing the pipe and valve arrangement at the bottom of the tank, shown in elevation in Figure 1, is illustrated by Figure 2. The component parts bear the same numerical designation as described in Figure 1. The arrangement of the valves I4 and I9 and the removable cover of the sealed chamber i 5 outside the tank, made necessary for the proper operation and cleaning of this gauge, are clearly shown. The relative positions of pipes I0 and I8 and the wells ZI and 22 for pipe I8 demonstrate the preferred embodiment where the gauging and sealing fluid is of a lower specific gravity than the contents of the container to be measured.

The preferred embodiment of my invention where the measuring fluid or sealing medium II] has a specific gravity higher than the specific gravity of the tank contents 20 is illustrated in Figure 3 where like numbers are used to denote like parts already shown and discussed in Figure 1. It will be noted that the structure as shown in Figure 1 is repeated with slight change except that the measuring tube containing the sealing or measuring liquid enters the bottom of sealed chamber l5 and the second tube it open to the tank contents enters the top of the sealed chamber, thereby placing the liquids in the relative positions of their respective specific gravities.

The detailed plan view of the elevation in Figure 3 is shown in Figure 4. In these two figures the wells which formed part oi the equipmentunder conditions of the sealing and measuring fiuid being of a lower specific gravity than the contents of the container illustrated in Figures 1. and. 2, are missing. as shown in Figure 4, the relative elevations of the measuring tube H5 and the second tube it, where they join the bottom of tank iii, are reversed. In the gauge illustrated, the sealing and measuring. fluid has a specific gravity greater than the tank contents and is therefore introduced into the sealed chamber [5 beneath the fluid to be measured, Pipe H is further modified by slot 23 which is in the under side of the extension Where it is shown inside the sealed L5. This slot 23 controls the flow of the fluid It, which is of a specific gravity higher than that of the tank contents, so that the stratificationer" the fluids is disturbed as little as possible.-

In operation, after it is determined what fluid shall be. as the measuring or sealing medium l-G, dependent on conditions of temperature, climate and the contents of the tank to be measured, the fiuid is poured into the measuring tube ll so as to fill the sealed chamber l5 which must have a volume at least as,v great as the volume oi measuring. tube H1. The measuring or sealing fluids will, in either case, displace'the tank contents which have filled the sealedchamber i i": to a point representative of. the depth of to be measured. In gauging. the level of the tank contents, valve i i and pressure cock H are closed, thereby locking the sealing fluid at a level which reflects the actual pressure conditions existing within the tank. Plug [3'' is. re moved. and a measuring stick (Fig. 5), Weighted tape or hollow tube calibrated. to allow for variance in specific gravities of the sealing liquid and the tank contents, is inserted. in measuring tube H. The true level of the tank contents. is then read. from the calibrated. measuring device. plug it is replaced and valves is and H. are opened... subjecting the. measuring fluid to the efiects of the normal tank conditions and. preparing the gauge for the next measuring, operation. Valve it in the second tube is used when it is necessary to removethe sealing or measuring fluid and clean the gauging apparatus. When the gauge is cleaned, valve it is closed, the eX- posed face plate of sealed chamber [5 is removed,

and the sealing. iiuid' is drained from the gauge b inging with it only that part of the tank cone to is which were in immediate contact with the sexing fluid. The loss of the tank contents is, therefore, t to a minimum and it is notnecesiii) . 4 the bottom of the tank and in communication with the measuring tube, apressureequalizingline connecting. the gas space. in the tank to the upper end or the measuring tube, a valve in the measuring tube adjacent said sealed chamber, the measuring tube and sealed chamber being adapted to contain a liquid of a specific gravity higher than the specific gravity of the tank contents, a second; tube. communicating with the sealed chamber andopen to the tank contents at the bottom of the tank, a valve in said second tube, and. a calibrated rod. adapted for insertion i said measuring tube.

2 A gauge for measuring levels of liquid contents in a tank comprising a measuring tube pass.- ing tlniough' the tank, a sealed chamber on: the bott nr of the tank and: in communication with the measuring tube, a pressure equalizing line comiecting the. gas space the tankv to the upper end of the measuring tube}. a vzail ve'in the measurtube adjacent said: sealed chamber, liquict in the measuring tube and sealed chamber at a specific gravity lower than the specific gravity of the tank. contents, a second tube communicating the sealed chamber and open. the t k cont its at the bottom of the tank, a. valve in sale coco? tube, and-a calibrated rod adapted for said measuring tube. A gaugefor measuring levels: of liquid c'ona: tank com-prising a measuring tube p s through the tank, a sea'iedi chamber on the bottom of the tank and in communicatioi-i with the measurhig tube, a pressure: equalizing 1 1e connecting the gas space in the tank to: the u er end of the measuring, tube, a valve in the measuring tube adjacent said sealed chamber, liquid in the measuring tube and sealed chamber of a. specific gravity difierent from the specific gravity of the tank contents, a second tube communicating with the sealed chamber and open tothe tank con-tents at-the bottom. of the a valve in said. second tube, and calibrated rod adapted insertion. in. saidmeas-uring tube.

4. A gauge tor measuring levels of liquid contents in a comprising. a. measuring tube within said. tank and projecting through the top thereof, chamber in. said tank communicating with; the lower end,v of the measuring tube, said measuring tube and chamber adapted to contain liquid of a specific gravity different the Specific. gravity of the tank contents, means for transferring. pressure of in the tank to the liquid the measuring tube tl-irough said chamber, means to equalize the pressure inthe gas 3 space of. the tank and the upper" end oi meas uring tube, liquid level locking means in the measuring tube and; a calibrated. rod: adapted for insertion in said measuring tube to Incas-me the liquid level: therein.

HAR'GLD A.- QUIST.

REFERENCES CITED The foil wing: references are of record in the file of. this patent:

UNITED STATES PATENTS Number Name Date 1.,256,9(4e Hurlbrink Feb. 19, 1918 1,259,680 Theobald Mar. 19; 13-13 1,5 SUI-58 Schri'ever .Dec. 29, 1925 1,670,207 Mtmphy May 15,. 1928 2,085,645 Staber July 13, L937 

